1. Field of the Invention
The present invention relates to a rotating electric machine, and particularly to a rotating electric machine having a multiphase coil including a plurality of phase coils.
2. Description of the Background Art
Various types of rotating electric machines, stators and the like with reduced vibrations for example have been proposed. Japanese Patent Laying-Open No. 2001-161048 for example discloses a rotating electric machine including a plurality of split cores and coils wound around winding mount portions formed at the split cores.
Stator teeth are formed at the split cores and each stator tooth has a flange formed at the top of the stator tooth. Japanese Patent Laying-Open No. 2007-135330 discloses a stator having a split core with a flange and a split core without flange that are alternately arranged.
Japanese Patent Laying-Open No. 2006-174651 discloses a stator including a plurality of split cores. Each split core includes a yoke element, a main portion formed at the center of the yoke element, and wing portions formed respectively on the right side and the left side of the main portion. The main portion and the right and left wing portions form a magnetic pole face.
Japanese Patent Laying-Open No. 2006-149167 discloses a stator including a plurality of stator teeth, and a rotating electric machine. At a circumferentially central portion of the top face of each stator tooth, an auxiliary groove extending in the axial direction is formed.
In the above-referenced conventional rotating electric machines each, a multiphase coil is wound around stator teeth. The multiphase coil includes U-phase, V-phase and W-phase coils, and alternating currents with different phases are supplied to respective phase coils.
The stator teeth include an inter-hetero-phase tooth, namely a tooth located between adjacent slots in which respective phase coils of different phases are inserted, and an inter-homo-phase tooth, namely a tooth located between adjacent slots in which respective phase coils of the same phase are inserted. In such a rotating electric machine, a magnetic flux is generated from each phase coil when alternating current is supplied to the phase coil. At this time, the state of flow of the magnetic flux formed by each phase coil in the inter-hetero-phase tooth and the state of flow of the magnetic flux in the inter-homo-phase tooth considerably differ from each other.
Further, the reluctance of a magnetic circuit when a magnetic flux from a magnet or the like provided in a rotor proceeds from the surface of the rotor and enters the inter-hetero-phase tooth is smaller than the reluctance of the magnetic circuit when the magnetic flux proceeds from the surface of the rotor and passes in the inter-homo-phase tooth.
Therefore, when the rotor rotates and the magnetic flux from the magnet enters the inter-hetero-phase tooth, the torque applied to the rotor suddenly increases, which is likely to cause vibrations and noise to the rotating electric machine.